Abstract: A workpiece holding device capable of processing a workpiece with high accuracy. A holding section 3 in a processing apparatus 1 is a workpiece holding device that rotatably holds a workpiece W to be processed with a grinding stone 21, the workpiece holding device including a base 34, a chuck 33 that is composed of a material exhibiting a lower thermal expansion coefficient than that of the base 34, is placed on the base 34, and can adsorb and hold the workpiece W, and a clamping member 40 that is attached to the base 34 with gaps G1 and G2 between itself and the chuck 33 in a radial direction D of the base 34 and presses a flange 36a of the chuck 33 against the base 34.

Abstract: A processing apparatus that flattens a workpiece to a desired thickness. A processing apparatus 1 that flattens a workpiece W having a non-circular shape with a grinding stone 21, the processing apparatus 1 including a suction member 33 capable of suction-holding the workpiece W, and an attachment 37 that is provided on an outer periphery side of the suction member 33. The attachment 37 is composed of a material harder to grind than the suction member 33, and can contact the grinding stone 21 during self-grinding for grinding the suction member 33.